Biomarkers are incorporated into cross-sectional, case-control and prospective cohort studies of occupational causes of cancer in order to enhance exposure assessment, provide insight into early biologic effects of specific chemicals, evaluate sources of genetic susceptibility and classify tumors at the molecular level to identify subgroups that may be more etiologically homogenous. Newly developed and on-going case-control studies of stomach, esophagus, brain, bladder, renal cell and breast cancer, NHL, and benzene-induced hematotoxicity and hematologic malignancies and cohort studies of women in China and agricultural workers in the United States are evaluating a range of potential genetic risk factors and their interaction with occupational and environmental exposures. Most of these studies are also collecting tumor samples for future molecular analyses. A study is being conducted in Norway to evaluate the relationships between serum levels for organochlorine chemicals and risk of specific cancers. A survey of about 200 largely African-American women in Trianna environmentally exposed to DDT from discharge from a pesticide manufacturing plant in the 1960s and 1970s is underway. A case-control study of women where serum levels of DDE/DDT are very high is being conducted in Shanghai. A population-based case-control study of renal cell cancer in areas of the U.S. with a high proportion of African American residents will be conducted to determine possible environmental exposures and genetic predisposition as reasons for the disproportionately higher risk African Americans have for developing renal cancer than Caucasians. A short-term follow-up study in corn farmers is being conducted to examine immune effects over a one-year period.